Current Status of Indole-Derived Marine Natural Products: Synthetic Approaches and Therapeutic Applications.

Indole is a versatile pharmacophore widely distributed in bioactive natural products. This privileged scaffold has been found in a variety of molecules isolated from marine organisms such as algae and sponges. Among these, indole alkaloids represent one of the biggest, most promising family of compounds, having shown a wide range of pharmacological properties including anti-inflammatory, antiviral, and anticancer activities. The aim of this review is to show the current scenario of marine indole alkaloid derivatives, covering not only the most common chemical structures but also their promising therapeutic applications as well as the new general synthetic routes developed during the last years.

Sustained use of marine subsidies promotes niche expansion in a wild felid.

The use of marine subsidies by terrestrial predators can facilitate substantial transfer of nutrients between marine and terrestrial ecosystems. Marine resource subsidies may have profound effects on predator ecology, influencing population and niche dynamics. Expanding niches of top consumers can impact ecosystem resilience and interspecific interactions, affecting predator-prey dynamics and competition. We investigate the occurrence, importance, and impact of marine resources on trophic ecology and niche dynamics in a highly generalist predator, the caracal (Caracal caracal), on the Cape Peninsula, South Africa. Caracals have flexible diets, feeding across a wide range of terrestrial and aquatic prey. We use carbon and nitrogen stable isotope analysis of fur samples (n = 75) to understand trophic position and niche shifts in coastal and inland foragers, as well as the implications of a diet rich in marine resources. We found significant differences in isotope signatures between these groups, with higher δ13C (P < 0.05) and δ15N values (P < 0.01) in coastal foragers. Isotope mixing models reveal that these elevated signatures were due to non-terrestrial food subsidies, where approximately a third of coastal foraging caracal diet comprised marine prey. The addition of marine prey species to diet increased both the trophic level and isotope niche size of coastal foraging caracals, with potential impacts on prey populations and competition. Our results suggest that marine prey are an important dietary resource for coastal foraging caracals, where seabirds, including two endangered species, are a major component of their diet. However, there are likely risks associated with these resource benefits, as routine consumption of seabirds is linked with higher pollutant burdens, particularly metals. Increased encounters between this terrestrial predator and seabirds may be a result of increased mainland colonies due to changes in habitat availability and the highly opportunistic and generalist foraging behaviour of a native predator.

Therapeutic Potential of Marine-Derived Cyclic Peptides as Antiparasitic Agents.

Parasitic diseases still compromise human health. Some of the currently available therapeutic drugs have limitations considering their adverse effects, questionable efficacy, and long treatment, which have encouraged drug resistance. There is an urgent need to find new, safe, effective, and affordable antiparasitic drugs. Marine-derived cyclic peptides have been increasingly screened as candidates for developing new drugs. Therefore, in this review, a systematic analysis of the scientific literature was performed and 25 marine-derived cyclic peptides with antiparasitic activity (1-25) were found. Antimalarial activity is the most reported (51%), followed by antileishmanial (27%) and antitrypanosomal (20%) activities. Some compounds showed promising antiparasitic activity at the nM scale, being active against various parasites. The mechanisms of action and targets for some of the compounds have been investigated, revealing different strategies against parasites.

Marine Plasmalogens: A Gift from the Sea with Benefits for Age-Associated Diseases.

Aging increases oxidative and inflammatory stress caused by a reduction in metabolism and clearance, thus leading to the development of age-associated diseases. The quality of our daily diet and exercise is important for the prevention of these diseases. Marine resources contain various valuable nutrients, and unique glycerophospholipid plasmalogens are found abundantly in some marine invertebrates, including ascidians. One of the major classes, the ethanolamine class (PlsEtn), exists in a high ratio to phospholipids in the brain and blood, while decreased levels have been reported in patients with age-associated diseases, including Alzheimer's disease. Animal studies have shown that the administration of marine PlsEtn prepared from marine invertebrates improved PlsEtn levels in the body and alleviated inflammation. Animal and human studies have reported that marine PlsEtn ameliorates cognitive impairment. In this review, we highlight the biological significance, relationships with age-associated diseases, food functions, and healthcare materials of plasmalogens based on recent knowledge and discuss the contribution of marine plasmalogens to health maintenance in aging.

Microalgae, Seaweeds and Aquatic Bacteria, Archaea, and Yeasts: Sources of Carotenoids with Potential Antioxidant and Anti-Inflammatory Health-Promoting Actions in the Sustainability Era.

Carotenoids are a large group of health-promoting compounds used in many industrial sectors, such as foods, feeds, pharmaceuticals, cosmetics, nutraceuticals, and colorants. Considering the global population growth and environmental challenges, it is essential to find new sustainable sources of carotenoids beyond those obtained from agriculture. This review focuses on the potential use of marine archaea, bacteria, algae, and yeast as biological factories of carotenoids. A wide variety of carotenoids, including novel ones, were identified in these organisms. The role of carotenoids in marine organisms and their potential health-promoting actions have also been discussed. Marine organisms have a great capacity to synthesize a wide variety of carotenoids, which can be obtained in a renewable manner without depleting natural resources. Thus, it is concluded that they represent a key sustainable source of carotenoids that could help Europe achieve its Green Deal and Recovery Plan. Additionally, the lack of standards, clinical studies, and toxicity analysis reduces the use of marine organisms as sources of traditional and novel carotenoids. Therefore, further research on the processing of marine organisms, the biosynthetic pathways, extraction procedures, and examination of their content is needed to increase carotenoid productivity, document their safety, and decrease costs for their industrial implementation.

Absolute Stereochemistry Determination of Bioactive Marine-Derived Cyclopeptides by Liquid Chromatography Methods: An Update Review (2018-2022).

Cyclopeptides are considered as one of the most important classes of compounds derived from marine sources, due to their structural diversity and a myriad of their biological and pharmacological activities. Since marine-derived cyclopeptides consist of different amino acids, many of which are non-proteinogenic, they possess various stereogenic centers. In this respect, the structure elucidation of new molecular scaffolds obtained from natural sources, including marine-derived cyclopeptides, can become a very challenging task. The determination of the absolute configurations of the amino acid residues is accomplished, in most cases, by performing acidic hydrolysis, followed by analyses by liquid chromatography (LC). In a continuation with the authors' previous publication, and to analyze the current trends, the present review covers recently published works (from January 2018 to November 2022) regarding new cyclopeptides from marine organisms, with a special focus on their biological/pharmacological activities and the absolute stereochemical assignment of the amino acid residues. Ninety-one unreported marine-derived cyclopeptides were identified during this period, most of which displayed anticancer or antimicrobial activities. Marfey's method, which involves LC, was found to be the most frequently used for this purpose.

Linking Coastal and Marine Resources Endowments and Climate Change Resilience of Tanzania Coastal Communities.

This paper presents findings on the links between coastal/marine resources endowment and climate change resilience to coastal communities in Mchungu and Kivinja' A' village on the coastal zone of Rufiji District in Tanzania. The study focused on exploring the existing coastal resources and their support to communities' livelihood, climatic threats that are experienced, and the role of coastal resources in enhancing communities' resilience. It further sought to establish other enabling factors for climate change adaptation (e.g., gender, education, governance, by-laws, and membership in social networks). The study used focus group discussions, key informant interviews, and household surveys in data collection. Findings show that Mchungu village is endowed with fish, mangrove, natural canal, and floodplains as their major coastal resources, while Kivinja' A' is rich in salt and coconut production. Communities in both villages exploit these coastal resources for their livelihood activities such as fishing, agriculture, and business. The study further found that coastal communities are already experiencing the effects of climate change through temperature rise, flooding, drought, sea-level rise, and storm surges. These affect household food security in terms of fish catch and crop production. The study revealed that coastal and marine resources were important for increasing community resilience (P ≤ 0.05) to climate change impacts in the studied villages. However, household resilience to climate change impacts was also influenced by gender, by-laws, education, and membership in social networks.

Seaweed bioactive compounds: Promising and safe inputs for the green synthesis of metal nanoparticles in the food industry.

Scientific research on developing and characterizing eco-friendly metal nanoparticles (NPs) is an active area experiencing currently a systematic and continuous growth. A variety of physical, chemical and more recently biological methods can be used for the synthesis of metal nanoparticles. Among them, reports supporting the potential use of algae in the NPs green synthesis, contribute with only a minor proportion, although seaweed was demonstrated to perform as a successful reducing and stabilizing agent. Thus, the first part of the present review depicts the up-to-date information on the use of algae extracts for the synthesis of metal nanoparticles, including a deep discussion of the certain advantages as well as some limitations of this synthesis route. In the second part, the available characterization techniques to unravel their inherent properties such as specific size, shape, composition, morphology and dispersibility are comprehensively described, to finally focus on the factors affecting their applications, bioactivity, potential toxic impact on living organisms and incorporation into food matrices or food packaging, as well as future prospects. The present article identifies the key knowledge gap in a systematic way highlighting the critical next steps in the green synthesis of metal NPs mediated by algae.

Socioeconomic disruptions of harmful algal blooms in indigenous communities: The case of Quinault Indian nation.

Harmful algal blooms (HABs) have been a pervasive challenge across coastal communities of the U.S. West Coast in recent years negatively affecting local economies and livelihoods. We focus on the effects of HABs to the Quinault Indian Nation (QIN) triggered by Pseudo-nitzschia that produce the toxin domoic acid (DA). This toxin accumulates in filter feeders and poses threats to human health via shellfish consumption. Consumption of razor clams with high levels of DA and Dungeness crab that prey on them can cause amnesic shellfish poisoning in humans and therefore requires closure of commercial, recreational and subsistence fisheries, postponing or limiting harvesting seasons. These disruptions result in significant losses in revenues along with negative effects to sociocultural dimensions of key importance to coastal communities. Livelihoods and wellbeing of tribal communities are affected disproportionately due to higher vulnerability and reliance on these marine resources for subsistence. We assess these effects at multiple levels for the QIN and discuss and reflect, through a tribal lens, upon advances and opportunities for impact mitigation and adaptation in the face of HABs, along with persisting challenges.

Marine resources and their value in Kadavu, Fiji.

Recognition of the multiple types of value of marine resources is crucial to help design locally meaningful and sustainable management approaches for marine and coastal habitats. There is a lack of information on the amount of living marine resources harvested by coastal communities in many Pacific Island Countries and Territories (PICTs), as well as on their economic and non-economic value. This paper explores the monetary, subsistence, and sociocultural value of selected marine resources (finfish and invertebrates) in Kadavu province, Fiji, based on a household survey and semi-structured interviews conducted in 2019 within one specific district. The paper provides estimates of the annual catch and monetary value of marine resources harvested by local communities at both the district and provincial levels, derived from catch and effort information collected from fishers and gleaners in situ. It also highlights the importance of integrating the sociocultural significance of marine resources into future value assessments.

The role of tropical small-scale fisheries in trace element delivery for a Small Island Developing State community, the Seychelles.

The concentrations of 13 trace elements were determined in 1032 muscles of 54 small-scale fisheries species collected from the Seychelles waters between 2013 and 2019. Overall, profiles were dominated by zinc (Zn) > arsenic (As) > iron (Fe) > copper (Cu) > selenium (Se), with the spiny lobsters, spanner crab and octopus exhibiting the highest levels of As, Cu and Zn while fish had higher Fe concentrations. Both taxonomy-dependent processes and ecological factors explained the interspecific differences of trace element profiles observed. A benefit-risk assessment revealed that crustaceans and cephalopods were good sources of Cu and Zn. One portion of any fish could provide 30-100 % of daily Se needs, and one portion of demersal and pelagic teleost fish could bring 5-20 % of Cu, Fe and Zn needs, especially for young adult and adult women. Finally, our analysis showed that there was very low health risks associated with small-scale fisheries consumption for the Seychelles population.

Recent Advances of Marine Sponge-Associated Microorganisms as a Source of Commercially Viable Natural Products.

Many industrially significant compounds have been derived from natural products in the environment. Research efforts so far have contributed to the discovery of beneficial natural products that have improved the quality of life on Earth. As one of the sources of natural products, marine sponges have been progressively recognised as microbial hotspots with reports of the sponges harbouring diverse microbial assemblages, genetic material, and metabolites with multiple industrial applications. Therefore, this paper aims at reviewing the recent literature (primarily published between 2016 and 2022) on the types and functions of natural products synthesised by sponge-associated microorganisms, thereby helping to bridge the gap between research and industrial applications. The metabolites that have been derived from sponge-associated microorganisms, mostly bacteria, fungi, and algae, have shown application prospects especially in medicine, cosmeceutical, environmental protection, and manufacturing industries. Sponge bacteria-derived natural products with medical properties harboured anticancer, antibacterial, antifungal, and antiviral functions. Efforts in re-identifying the origin of known and future sponge-sourced natural products would further clarify the roles and significance of microbes within marine sponges.

Building bridges between natural and social science disciplines: a standardized methodology to combine data on ecosystem quality trends.

Despite a growing interest in interdisciplinary research, systematic ways of how to integrate data from different disciplines are still scarce. We argue that successful resource management relies on two key data sources: natural science data, which represents ecosystem structure and processes, and social science data, which describes people's perceptions and understanding. Both are vital, mutually complementing information sources that can underpin the development of feasible and effective policies and management interventions. To harvest the added value of combined knowledge, a uniform scaling system is needed. In this paper, we propose a standardized methodology to connect and explore different types of quantitative data from the natural and social sciences reflecting temporal trends in ecosystem quality. We demonstrate this methodology with different types of data such as fisheries stocks and mangrove cover on the one hand and community's perceptions on the other. The example data are collected from three United Nations Educational Scientific and Cultural Organization (UNESCO) Biosphere reserves and one marine park in Southeast Asia. To easily identify patterns of convergence or divergence among the datasets, we propose heat maps using colour codes and icons for language- and education-independent understandability. Finally, we discuss the limitations as well as potential implications for resource management and the accompanying communication strategies. This article is part of the theme issue 'Nurturing resilient marine ecosystems'.

Toward Food Sovereignty for Coastal Communities of Eastern Québec: Co-designing A Website to Support Consumption of Edible Resources from the St. Lawrence River, Estuary, and Gulf.

Background. Despite the abundance and proximity of edible marine resources, coastal communities along the St. Lawrence in Eastern Québec rarely consume these resources. Within a community-based food sovereignty project, Manger notre Saint-Laurent ("Sustenance from our St. Lawrence"), members of participating communities (3 non-Indigenous, 1 Indigenous) identified a need for a web-based decision tool to help make informed consumption choices. Methods. We thus aimed to co-design a prototype website that facilitates informed choices about consuming local edible marine resources based on seasonal and regional availability, food safety, nutrition, and sustainability, with community members, regional stakeholders, and experts in user experience design and web development. We conducted 48 interviews with a variety of people over 3 iterative cycles, assessing the prototype's ease of use with a validated measure, the System Usability Scale. Results. Community members, regional stakeholders, and other experts identified problematic elements in initial versions of the website (e.g., confusing symbols). We resolved issues and added features people identified as useful. Usability scores reached "best imaginable" for both the second and the third versions and did not differ significantly between sociodemographic groups. The final prototype includes a tool to explore each species and index cards to regroup accurate evidence relevant to each species. Conclusions. Engaging co-designers with different sociodemographic characteristics brought together a variety of perspectives. Several components would not have been included without co-designers' input; other components were greatly improved thanks to their feedback. Co-design approaches in research and intervention development are preferable to foster the inclusion of a variety of people. Once the prototype is programmed and available online, we hope to evaluate the website to determine its effects on food choices.

Contribution to Mediterranean medieval dietary studies: Stable carbon and nitrogen isotope data of marine and catadromous fish from Provence (9th-14th CE).

Whilst marine resources are one of the pillars of the Mediterranean diet, their mode of acquisition and subsequent consumption by medieval populations in southern France are still not well known. Throughout Europe, bioarchaeological techniques, however, are beginning to reveal hitherto unknown aspects of these practices both dating to the medieval period as well as other periods of history and prehistory. This study involved the stable isotope analysis of five marine and catadromous taxa from three medieval sites in Provence, France: "rue Frédéric Mistral" at Fos-sur-Mer, "le Château" at Hyères and "Couvent des Dominicaines - Parking/Collège Mignet" at Aix-en-Provence. In total, 127 specimens, including Anguilla anguilla, Dicentrarchus labrax, Sparus aurata, Diplodus sargus and Mugilidae were subjected to carbon and nitrogen stable isotope analysis. The study provides a crucial and unprecedented point of reference of the carbon and nitrogen isotopic variability of one of the main dietary resources in the Mediterranean world, fish.

New challenges for the Human Oceans Past agenda.

We contend that the harvest of marine resources played a critical, but as yet underappreciated and poorly understood, role in global history. In a review of the field of marine environmental history and archaeology we conclude that while much progress has been made, especially in the last two decades, fundamental questions remain unanswered. In order to make full use of the rapid growth of Big Data and ongoing methodological breakthroughs there is a need for collaborative and comparative research. Such joint efforts on a global scale must be guided by a focus on common, simple yet challenging, questions. We propose a Human Oceans Past research agenda to call for multi- and trans-disciplinary archaeological, historical and palaeoenvironmental/palaeoecological research to investigate: (1) when and where marine exploitation was of significance to human society; (2) how selected major socio-economic, cultural, and environmental forces variously constrained and enabled marine exploitation; and (3) what were the consequences of marine resource exploitation for societal development. We contend that this agenda will lead to a fundamental revision in our understanding of the historical role of marine resources in the development of human societies.

Bioprospecting marine actinomycetes for antileishmanial drugs: current perspectives and future prospects.

Revived analysis interests in natural products in the hope of discovering new and novel antileishmanial drug leads have been driven partially by the increasing incidence of drug resistance. However, the search for novel chemotherapeutics to combat drug resistance had previously concentrated on the terrestrial environment. As a result, the marine environment was often overlooked. For example, actinomycetes are an immensely important group of bacteria for antibiotic production, producing two-thirds of the known antibiotics. However, these bacteria have been isolated primarily from terrestrial sources. Consequently, there have been revived efforts to discover new compounds from uncharted or uncommon environments like the marine ecosystem. Isolation, purification and structure elucidation of target compounds from complex metabolic extract are major challenges in natural products chemistry. As a result, marine-derived natural products from actinomycetes that have antileishmanial bioactivity potentials have been understudied. This review highlights metagenomic and bioassay approaches which could help streamline the drug discovery process thereby greatly reducing time and cost of dereplication to identify suitable antileishmanial drug candidates.

Recovery of assessed global fish stocks remains uncertain.

Concerns over overexploitation have fueled an ongoing debate on the current state and future prospects of global capture fisheries, associated threats to marine biodiversity, and declining yields available for human consumption. Management reforms have aimed to reduce fishing pressure and recover depleted stocks to biomass and exploitation rates that allow for maximum sustainable yield. Recent analyses suggest that scientifically assessed stocks, contributing over half of global marine fish catch, have, on average, reached or even exceeded these targets, suggesting a fundamental shift in the effectiveness of fisheries governance. However, such conclusions are based on calculations requiring specific choices to average over high interstock variability to derive a global trend. Here we evaluate the robustness of these conclusions by examining the distribution of recovery rates across individual stocks and by applying a diversity of plausible averaging techniques. We show that different methods produce markedly divergent trajectories of global fisheries status, with 4 of 10 methods suggesting that recovery has not yet been achieved, with up to 48% of individual stocks remaining below biomass targets and 40% exploited above sustainable rates. Furthermore, recent rates of recovery are only marginally different from zero, with up to 46% of individual stocks trending downward in biomass and 29% of stocks trending upward in exploitation rate. These results caution against overoptimistic assessments of fisheries writ large and support a precautionary management approach to ensure full rebuilding of depleted fisheries worldwide.

Modeling of the Ecological Carrying Index of reclaimed land in coastal city: A sustainable marine ecology perspective.

In recent years, Wenzhou City located on the southeast coast of China has experienced the largest scale of land reclamation projects in China. However, the extent to which such projects still bring about the destruction of marine resources and the environment. So, in this study, a marine ecological development carrying capacity index model was established and analyzed the ecological carrying capacity index of the reclaimed sea area in Wenzhou with the detection and warning conditions to propose a marine ecological protection supervision mechanism. By the proposed mechanism, five primary-level indicators and 10 corresponding secondary-level indicators were established. The obtained results showed that the ecological carrying index of the reclaimed area in Wenzhou falls within the range, 2.35-5.45, which is indicative of small geographic differences. These results suggest that in future, a detection and early warning mechanism for the determination of the ecological carrying capacity of reclaimed sea areas should be established. Furthermore, the strict implementation of the reclamation project development evaluation management control system is recommended, and it is also necessary to reasonably adjust the planning and construction of the sea area.

Seaweeds as Valuable Sources of Essential Fatty Acids for Human Nutrition.

The overexploitation of terrestrial habitats, combined with the ever-growing demand for food, has led to the search for alternative food sources. The importance of seaweeds as food sources has been growing, and their potential as sources of fatty acids (FA) make seaweeds an interesting feedstock for the food and nutraceutical industries. The aim of this study is to assess the potential of five red seaweeds (Asparagospis armata, Calliblepharis jubata, Chondracanthus teedei var. lusitanicus, Gracilaria gracilis, and Grateloupia turuturu) and three brown seaweeds (Colpomenia peregrina, Sargassum muticum and Undaria pinnatifida), harvested in central Portugal, as effective sources of essential FA for food or as dietary supplements. FA were extracted from the biomass, transmethylated to methyl esters, and analyzed through gas chromatography-mass spectrometry. G. gracilis presented the highest content of saturated fatty acids (SFA) (41.49 mg·g-1), whereas C. jubata exhibited the highest content of highly unsaturated fatty acids (HUFA) (28.56 mg·g-1); the three G. turuturu life cycle stages presented prominent SFA and HUFA contents. Omega-6/omega-3 ratios were assessed and, in combination with PUFA+HUFA/SFA ratios, it is suggested that C. jubata and U. pinnatifida may be the algae with highest nutraceutical potential, promoting health benefits and contributing to a balanced dietary intake of fatty acids.